Accompanied with the trend of communication using broader band and higher frequency, the performance of related audio and optical communication devices have to be largely improved. Since the single crystal ferroelectric materials have excellence photoelectric characteristics, they are widely used in the audio and optical communication devices.
The current commercialized single crystal ferroelectric wafer with about 300˜500 um in thickness can no longer satisfy the requirements of advanced communication devices. In the recent research reports, a high performance device of which the frequency is 3˜4 times faster than that of the present devices can be manufactured using the substrate made of ultra-thin single crystal ferroelectric material. For example, professor Osgood uses the Lithium Niobate single crystal substrate with only several micrometer in thickness to manufacture a photoelectric modulator of which the operating frequency can reach 80 GHz or higher. On the other hand, the operating frequency of the present photoelectric modulator using the conventional substrate can only reach 20 GHz.
Obviously, to satisfy the communication requirement of higher and wider frequency, the most efficient and economical way is to use ultra thin substrates for manufacturing those relating devices.
The conventional wafer process can only manufacture wafers of at least several hundred micrometers in thickness, or else the clipping and loading issues have to be overcome while manufacturing ultra-thin wafers. Moreover, the thin wafers are easily broken during the posterior processes. Please refer to FIG. 1A to FIG. 1D, showing the conventional method for manufacturing an ultra-thin single crystal ferroelectric film disclosed in U.S. Pat. Nos. 6,540,827B1 and 6641662B2. As shown in the figures, ions 101 are implanted into a single crystal ferroelectric wafer 100 to generate a metamorphosis layer 102. Then, the metamorphosis layer 102 is removed by the thermal process and chemical etching process so as to complete an ultra-thin single crystal ferroelectric film 100a. 
In summary, the conventional method for manufacturing an ultra-thin single crystal ferroelectric film exists at least the following shortcomings:    1. The conventional method adopts the process of single crystal ion cutting such that the cost of equipments required in the process is increased and thus the competitiveness is decreased.    2. The control conditions of the conventional method are much stricter, that cause the process to be much complicated and has affect on the capability of mass production.    3. The conventional method has no carrier wafer to hold the produced ultra-thin single crystal ferroelectric film such that the single crystal ferroelectric film is easily broken and thus the yield of the process is reduced.